Solid-state image sensors, for example, image sensors have been used for taking images. Further, in recent years, touch panels with input functions obtained by making display devices have image pickup functions have attracted attention. Touch panels are display devices which can be operated when fingers or the like directly touch panels. The touch panels are also referred to as touch screens, for example.
In order to make display devices have image pickup functions, photo sensors are provided in display regions. Thus, the display regions can also serve as input regions. For example, Reference 1 discloses a semiconductor device with an image capture function.